The objective of the proposed application is to develop a dual functional probe which is detectable at single-particle level for both Raman and fluorescence microscopy, so that the strengths of each technique can be combined into a single imaging tool for tackling challenges in bioimaging. With this new imaging probe and tool, we plan to address a long-term bioimaging challenge that is real-time imaging of interactions between ligands and receptors at the molecular level inside live cells. Success of this proposed work will (1) provide a new imaging probe that is not only highly fluorescent and robust but can also report molecular information for ligands it labels; (2) offer a new imaging tool which integrates strengths of fluorescence microscopy and Raman spectroscopy; (3) enable us to correlate cellular dynamics of ligands with ligand-binding protein interactions at the chemical level inside live cells. The applications of these fluorescent and Raman probes are not limited to the proposed studies; they can also find applications in bioimaging as multiplexing and multifunctional probes to correlate fluorescence and Raman images with electron microscopy images at in vitro and in vivo level. PUBLIC HEALTH RELEVANCE: Ligand-receptor interactions play a pivotal role in regulating cellular functions and provide a foundation for disease diagnosis and new therapy development. However, comprehensive understanding of in vivo interactions between ligand and receptors at the molecular level remains highly challenging. Our research application aims to integrate fluorescence microscopy with Raman spectroscopy using a dual functional probe, so that we can simultaneously track and chemically image of ligand-receptor complexes at the single-cell level inside live cells. Success of this proposed work will (1) provide a new imaging probe that not only is highly fluorescent and robust but also can report molecular information of ligands it labels; (2) offer a new imaging tool which integrate strengths of fluorescence microscopy and Raman spectroscopy; (3) enable us to correlate cellular dynamics of ligands with ligand-receptor interactions at the chemical level inside live cells.